Time for action – creating matrices

Matrices can be created with the mat function. This function does not make a copy if the input is already a matrix or an ndarray. Calling this function is equivalent to calling matrix(data, copy=False). We will also demonstrate transposing and inverting matrices.

1. Rows are delimited by a semicolon, values by a space. Call the mat function with the following string to create a matrix:

   A = np.mat('1 2 3; 4 5 6; 7 8 9')
   print "Creation from string", A

   The matrix output should be the following matrix:

   Creation from string [[1 2 3]
    [4 5 6]
    [7 8 9]]
   

2. Transpose the matrix with the T attribute, as follows:

   print "transpose A", A.T

   The following is the transposed matrix:

   transpose A [[1 4 7]
    [2 5 8]
    [3 6 9]]
   

3. The matrix can be inverted with the I attribute, as follows:

   print "Inverse A", A.I

   The inverse matrix is printed as follows (be warned that this is a O(n3) operation):

   Inverse A [[ -4.50359963e+15   9.00719925e+15  -4.50359963e+15]
    [  9.00719925e+15  -1.80143985e...